Extraction process for ni,cu,cr and co



United States Patent EXTRACTION PROCESS FOR Ni, Cu, Cr AND Co John D. Watson, Sr., and William A. Mod, Lake Jackson, Tex., and Fred N. Teumac, South Bend, Ind., assiguors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 528,828, Feb. 21, 1966. This application Dec.16, 1968, Ser. No. 784,244

Int. Cl. C221) 3/00; C01g 53/04, 3/02 U.S. Cl. 75-101 11 Claims ABSTRACT OF THE DISCLOSURE A method for the extraction of nickel, copper, chromium and cobalt metal values from ores containing their sulfide and/or their oxide and silicate salts comprising contacting said ores with an aqueous leach solution which contains polyalkylenepolyamines or polyalkylenimines, or mixtures thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS This is a continuation-in-part of application Ser. No. 528,828 filed Feb. 21, 1966' now abandoned.

BACKGROUND OF THE INVENTION The art teaches a number of methods for the extraction of nickel, copper, chromium and cobalt metal values from their ores. The methods usually involve a leaching step in which the desired metal is extracted from the metal-bearing material and dissolved in the leach solution.

One such leaching process is the utilization of aqueous sulfuric acid to extract copper oxide from low grade copper oxide ores. While sulfuric acid is effective as a solvent, has a low cost and is relatively non-volatile, it does dissolve other metals, particularly iron, which creates problems of selectivity, i.e., purity of the resulting dissolved copper, and the corrosion of materials of construction. Hydrochloric acid is also used to extract copper oxide, but presents the additional problem of high volatility.

A well-known process for the treatment of nickeliferous ores is the Shern'tt-Gordon process, which consists of digesting the ores with ammonium hydroxide under pressure and high temperature, and then using a solvent, such as organic esters of phosphoric acid, to extract and separate metal values from the ammonium leach solution.

SUMMARY OF THE INVENTION The instant invention is a method for the extraction of nickel, copper, chromium and cobalt metal values from ores containing their sulfide and/ or their oxide and silicate salts, said method comprising contacting the ore with an aqueous solution of a polyalkylenepolyamine or polyalkylenimine, or mixtures thereof, whereby the metal values are extracted.

The instant invention results in some surprising separations. For instance, copper oxide can be preferentially extracted from ores containing both copper oxide and nickel oxide, even where present in proportions as low as 0.10 percent. And nickel, copper, chromium and cobalt sulfides can be preferentially extracted from ores containing iron sulfides, even though iron sulfide is the most soluble in water.

Extractions can be effected by either adding an aqueous solution of a polyalkylenepolyamine or polyalkylenimine, or mixtures thereof (hereinafter collectively called amines), to a slurry of the metal ore, or by so called in situ leaching, i.e., pumping an aqueous solution of the electrolyte into the mineral containing ore deposit. The leaching solution so used should generally contain "ice from about 0.1 to 50 weight percent of the amine, the remainder being essentially H O. The optimum concentration for the extraction of metal sulfides is about 1 weight percent. For the extraction of copper oxide, the amine solution should contain from about 2 to 4 or more grams of amine per gram of copper oxide present in the ore, preferably from about 2.5 to 3.5 grams. Excess may be added but is not more advantageous.

The metal values can then be recovered both directly from the aqueous phase, by, for instance, electrolysis, reduction with a reducing gas and other well-known chemical methods for recovering these particular metal values.

The extraction of nickel, copper, chromium and cobalt sulfides and/or oxides and silicates by the method of this invention can suitably occur from a pH of about 2 to about 12. It is to be noted that copper oxide is much more soluble at low pH values, and thus best results for its extraction are obtained at a pH of about 2 to 7, while NiO becomes more soluble as the pH increases above 7. The pH of the amine solution can be adjusted with an acid or a base. Preferable for such adjustments are the mineral acids, such as HCl and H 50 and bases such as NaOH and NH OH. Other pH adjustors are, for example, phosphoric acid and nitric acid.

The process of this invention is operable from about 0 C. to about the boiling point of the amine solution used. For the extraction of nickel, copper, chromium and cobalt sulfides, a temperature of 0 to 40 C. is suitable, and a temperature of 10 to 30 C. is preferred. For the extraction of copper oxide, a temperature of from about 25 to C. is preferred.

Water-soluble polyalkylenepolyamines (PAPA) and polyalkylenimines (PAI) in general are effective in the process of this invention. PAPA or PAI having higher nitrogen to carbon ratios are the most effective, that is, polyethylenimine is more effective than polypropylenimine.

If polyethylenimine (PEI) is employed in the present invention, it may be prepared by the polymerization of ethylenimine. Methods for such polymerization are known in the art, and are reviewed by Jones, Polymerization of Olefin Imines, in Plesch, ed., The Chemistry of Cationic Polymerization (New York, MacMillan, 1963), pages 521 to 534. The molecular weight of the PEI is not critical, but the difficulty of handling extremely viscous polymer solutions makes very high molecular weight PEI less desirable. The PEI utilized in this invention may range from the dimers, trimers, and tetramers to PEI having an average molecular weight of 100,000 or more. The upper limit of the molecular weight is determined solely by the water solubility and viscosity of the PEI.

Lower molecular weight PAPA and PAI, such as dimers, trimers and teramers, give a performance equivalent to higher molecular weight PAPA or PAI but with shorter reaction time. The lower molecular weight PAI or PAPA are commercially available. Mixtures of PAPA and/or PAI are also operable in the process of this invention.

It is to be noted, particularly from Example 11, that the addition of air to the ore/aqueous amine can increase the weight percent extracted in a dramatic fashion. Air can be bubbled, for instance, through the slurry while digesting in the extraction solution.

SPECIFIC EXAMPLES Example 1 The solubility of copper oxide in a 5 percent by weight aqueous solution of PEI having a molecular weight generally above 100,000 was evaluated at varying pH values and temperatures. The pH was adjusted with aqueous HCl. The results show that copper oxide is much more soluble at lower pH values and its solubility increases with temperature in the range evaluated. The results obtained are listed below in Table I, expressed as grams of copper oxide solubilized per gram of PEI in the 4 Example 5 Runs were made using aqueous solutions containing the polyalkylenepolyamines (PAPA) without the addition of acid. Ten grams of a mixture consisting of 97.9

leach solution 5 weight percent M0, 1.3 Weight percent CuO, and 0.8 weight percent Fe O were added to a beaker. Two grams of TETA were added to sufiicient water to give a 100 cc. solution and added to the mixture. This mixture had a TABLE I pH of about 11.2. The resulting mixture was constantly pH agitated for four days. An analysis of the liquids showed 82 70 55 that 66 percent of the CuO was removed while only about 0 one percent of the NiO was removed.' No iron was Grams PEI detected in the liquid. o Two grams of a mixture consisting of, by weight, 90 Temzgemmm (L25 (L85 Q91 percent MO, 5 percent CuO, and 5 percent Fe O was 0.38 0. 59 9. 33 added to a beaker. A solution of 2 grams of pentaethylenehexamine (PEHA) in sufiicient water to make up to 100 cc. was added to the mixture. This mixture had a pH of about 11.5. The resulting mixture was agitated constantly for three days at room temperature. An analysis Example 2 of the liquid showed that 70 percent of the CuO was h f d d k l d d removed and less than one percent of the nickel and iron One gram eac o pow ere 1116 e 0x1 e an copper oxides was removed. oxide were thoroughly mixed and added to a beaker. 1g E l 6 T TA a $121 .25.it???tissfisirattrtsdd of H Ol To test the effect of P 801mm. 9 copper made up to 50 cc with Water and added to the 10 grams of a copper latente ore containing 0.8 weight beaker. The resulting mixture had a pH of 8.7. The conpe.rcent copper as F oxlde was placed m a bPaker tents were continuously agitated for 24 hours. Analysis 3 3 2 i i: 9. 2 of 22i a 2 2 of the liquid product by emission spectrography indicated a a P o 18 mlx q agl e or ay that 72 percent by weight of the copper oxide had been at room temperature. An ana ysis sf owed 1that 56.5 perremoved, but only 1.1 percent by weight of the nickel cent of the copper was extracted mm t e oxide had been removed. Ex mple 7 Example 3 A quantity of 77 grams of MO and one gram of CuO S aratio of co er from a mixture containing by were thoroughly mixed and added to a large flask. A g 1 3 n rcent s r oxide 97 9 ercem nickel one percent solution in water of PEI having an average g' spgercent g with g Solution con molecular weight above 100,000 was acidified with HCl to J, 2 3 a. pH or 4. One liter of this solution was added to the 1.223332%; 32:53.:.rwrgra ssaa 4 a how at 000 t d ov a H ran 6 of about 2 5 room temperature. An analysis of the liquids showed g gg gz z i pp y that 7l52percent off tllile g pper oxide was removed while cent of the nickel was removed over a 72-hour period at on y percent 0 t e 10 was removed' pH 2.5. The residue of the mixture analyzed 0.16 weight Example 8 percent copper. TETA gave sim lar res l s to those Five grams of a nickeliferous laterite ore (Red Mounfaffled PEI except eqlflvalellt results were P tain ore) pulverized to less than 100 mesh was mixed tamed In 24 P A Welght Tail? of TETA to pp 111 with 100 ml. of a 2 percent solution of PEHA solution,

the leach Solutlon 0f Was Obtamcdcontinuously agitated, pH adjusted to about 2.0 using Example 4 concentrated HCl, and digested at about 24 C. for 72 hours. At the end of this time, the aqueous solution was mftzd z tzi arsazraranesthesia; g gq rgfi g 1101'1, c romium an co at. e ana YSlS o t e ore runs with temperature as the only variable. A quantity of and the results of the extraction are shown below i g s zi g g tfi y gg g ig ggg g g g Analysis of Red Mountain Ore (nickeliferous laterite):

Aqueous solutions containing one gram of TETA and Percent 2.71 grams of 37 weight percent aqueous HCl were made F 0 54.9

up to 50 cc. with water and added to each beaker. S10 16.1

These solutions had a pH of 2.6. Both were constantly M 6,2

agitated for 24 hours. One solution was kept at room A1 0 3.4

temperature and the other maintained near the boiling point C.). The same sequence of operations was Present as oxldes. t slhcateis' I Percent repeated with one gram of 98-99 weight percent aqueous Cr 1.7

H 80 substituted for the HCl, giving the resulting solu- Ni 1.0

tions a pH of 4.5. The results of these runs are shown Mn 0.5

in Table II. Co 0.14

TABLE II Percent Percent Percent (Weight Fe re- CuO N10 F8203 moved/Weight Temperature Removed Removed Removed Cu Removed) Acid Addition:

H01 50 0.29 0.6 0.004 H01- 100 1. 50 0. 9 0. 002 H2504 53 0.23 0.7 0.004 HZS 04.. 100 10. 0 0. 4 0. 001

Also trace amounts of Ca, T1, V, Zn, and Cu values. weight percent of metal extracted. In all the runs, agitation was employed throughout the treating steps.

TABLE III Parts Percent of Metal of Time Extracted Ore in Air Treated Extracting Solution Used Temp., 0. Hours Added Fe Co Cu Ni 5 100 parts of 1% TETA 23 120 Yes---" 0. 04 90 14. 3 39. 2 5 100 parts of 1% TETA. 23 21.4 42. 8 5 100 parts of 1% TETA 23 3. 1.18 100 parts of 1% TETA 23 3. 0 l. 18 5 100 parts of 2% TETA 23 3. 0 1. 25 5 200 parts of 1% TETA 23 20. 0 71. 5 5 100 parts of 2% TETA 23 20. 0 50. 0 5 200 parts of 1% PEHA 23 4. 0 57. 0 500 parts of 2% TETA" 70-73 43.0 89. 0 20 500 parts of 2% TETA. 70-73 55. 0 100. 0 50 500 parts of 5% TETA 90 1.14 14. 3 50 500 parts of 5% TETA. 90 6. 0 37. 4 20 500 parts of 1% TETA 80 32.0 67.0 20 500 parts of 1% PEHA 80 14. 0 31.0 20 500 parts of 1% TETA cont 83 0. 7 35. 8 20 500 parts of 1% TETA 80 15. 0 40. 0 20 500 parts of 1% DETA l 78 36. 0 71. 0 20 500 parts of 1% DETA 78 48 Yes 0. 05 40 25. 0 75. 0

1 Diethylenetriamine.

The remainder was unidentified combustible or vaporizable material.

Amount found Percent by analysis in (by Amount in the ore, calculated from the the aqueous weight) above ore analysis phase extracted Ni,0.05 grams Ni, .003 grams... 6 00,0.007 grams.. 86 Fe,1.75 grams 1. 65 Cr,0.085 gram 47 Cu,Trace Cu, Trace Example 9 Example 8 was repeated except that the pH of the electrolytic solution was adjusted with NaOH pellets to the adjusted pH of between about 11.0 and 12.0. The results are shown below:

Amount found by analysis Percent (by weight) in the aqueous phase: Extracted Ni .001 gm 2 Co .002 gm. 3

Fe .0025 gm. 02

Cr .04 gm. 47

Cu trace.

Example 10 Ten grams of pulverized Pentlandite ore (ca 70-150 mesh) was mixed with 50 ml. of 1 percent TETA solution. The mixture was agitated at about 24 C. for 72 hours with samplings taken every 24 hours for analysis of cobalt, copper, nickel and iron. The results are shown below:

Amount found in Aqueous Phase Cale. from analysis Percent of samplings extracted Amount ut into aqueous after mixture calc. from ore anal.) 24 hrs. 48 hrs. 72 hrs. 72 hrs Example 11 What is claimed is:

1. A process for the chemical extraction of nickel, copper, chromium and cobalt metal values from ores containing their sulfide and/ or their oxide and silicate salts, comprising contacting said ore with an aqueous solution of a polyalkylenepolyamine or polyalkylenimine, or a mixture thereof.

2. The process of claim 1 wherein the polyalkylenepolyamine is diethylenetriamine, triethylenetetramine or pentaethylenehexamine.

3. The process of claim 1 wherein air is contacted with the ore during extraction.

4. The process of claim 1 wherein the pH is adjusted to about 2 to 12 with an acid or a base.

5. The process of claim 1 wherein the aqueous solution consists essentially of water and from 0.10 to 50.0 weight percent polyalkylenepolyamine or polyalkylenimine, or mixtures thereof.

6. The process of claim 1 wherein the polyalkylenimine is polyethylenimine or polypropylenimine.

7. A process for the chemical extraction of copper oxide from a copper oxide-containing mineral mixture which comprises contacting said mixture with a leaching solution consisting essentially of water and at least about one percent by weight, based on the solution, of a watersoluble polyalkylenepolyamine or polyalkylenimine or a mixture thereof.

8. The process of claim 7 wherein the polyalkylenepolyamine is diethylenetriamine, triethylenetetramine or pentaethylenehexarrnne.

9. The process of claim 7 wherein the polyalkylenimine is polyethylenimine or polypropylenimine.

10. The process of claim 7 wherein the polyalkylenepolyamine is triethylenetetramine or pentaethylenehexamine, and the pH of its aqueous solution is adjusted to about 2 to about 7 with a mineral acid.

11. The process of claim 7 wherein the polyalkylenimine is polyethylenimine having an average molecular weight of 100,000 or more, and the pH of its aqueous solution is adjusted to about 2 to about 7 with a mineral acid.

References Cited UNITED STATES PATENTS 2,839,387 6/1958 Burton 75-105 2,950,964 8/1960 Forward et al 75103 3,201,334 8/1965 Ben-Bassat 75-117 L. DEWAYNE RUTLEDGE, Primary Examiner T. R. FRYE, Assistant Examiner US. Cl. X.R. 

